Yes, I experience vascular tumescence of the phallus every so often while in diapers 24/7.
It is a normal part of the functioning of the male hominid primate body.
I just ignore it whenever it happens and just fill my mind with thoughts of being little and helpless.

This really isn't as big an issue as people make it out to be. Yes, some people get an erection or sexually stimulated while in little mode/thinking about/wearing diapers. Yes, your body is naturally reacting to some kind of pleasurable stimulation. No, this does not make you a pedophile. No, this does not mean you're a filthy individual. No this does not mean you are disgusting.

Random funfact: Even children, get erections. Even infants, can get an erection. Infant boys can get several erections at night while asleep due to the body's natural way of doing things the way it does it biologically. An erection should not bring you out of little mode. Arousal is something everyone deals with, even children, the only difference with children is, children don't understand what it is yet or have a comprehension of whats going on to do anything about it. People are going to get erections, this isn't a bad thing. This is telling you that your body is working NORMALLY.